CrazyNeutrino said:
Australian telescope has detected white dwarf star in the process of destroying solar system
AN Aussie planet watcher has detected what can only be described as The Walking Dead of the astronomy world.
A small Australian factory-built robotic telescope in the Arizona desert has detected a dense, white dwarf star in the process of ripping several planets to smithereens.
The findings from the zombie star are the first observation of a solar system in its last legs and have been published in the journal Nature.
more…
> planets being destroyed and dumping material on the white dwarf was the best explanation for the detection of these heavy elements.
But far from the only explanation. White dwarf atmospheres can be and are wildly different from one another. Some white dwarfs have an atmosphere of nearly pure hydrogen, others nearly pure helium, others have atmospheres consisting mostly of heavy elements, carbon and above. The interior of a white dwarf largely consists of carbon and above, and what is in the atmosphere above that tends to depend on how catastrophic the process that formed the white dwarf was.
For a classification of white dwarf atmospheres, see https://en.wikipedia.org/wiki/White_dwarf#Atmosphere_and_spectra
Catastrophic events that can alter a white dwarf atmosphere include include:
Factors associated with the size of the progenitor star, because some white dwarfs come from supernovae.
Gravitational attraction of material shed in later red-giant stages.
Effect of previous planetary nebula phase.
Passing through a molecular cloud in the galaxy.
Accretion of matter from a nearby star.
or, as claimed above,
Accretion of matter from a nearby planet.
Some white dwarfs are cataclysmic variables, and some are regular variables like ZZ-Ceti (this latter when they fall in the instabilitry strop on the H-R diagram). All this affects the presence or absence of spectral lines of heavy elements in its atmosphere.